Nearly 2 billion people (mostly in Africa, South East Asia and Latin America) have inadequate iodine nutrition. Pregnant women and children are most at risk from iodine deficiency disorders (IDD), which occur as a range of abnormalities including hypothyroidism which impairs mental development in the fetus and in infants. Iodine deficiency disorders have been greatly reduced in industrialized countries through routine addition of iodine to table salt, a practice that started in the 1920's. Recently, the internationa health community has been striving to implement salt iodization programs in the rural areas of developing counties where the populations remain at risk from IDD. There are many challenges. Developing countries are typically served by a network of individual artisanal salt producers using low tech production methods and poorly administered distribution channels. In these situations international and regional health agencies need viable methods to check salt iodine levels in the field at multiple salt production sites and at points along the distribution chain. Laboratory test methods cannot be used in these situations and existing test kits for iodine have significant limitations. Lacking critical information whether their efforts to introduce iodine int salt at the prescribed levels are succeeding, IDD intervention programs can become ineffective or breakdown entirely. Working with coordinators from the International Council for the Control of Iodine Deficiency Disorders (ICCIDD) we have devised a salt iodine test kit specifically for low resource (rural) settings in developing countries. The test kit uses dry (stable) test reagents tha are incorporated into a uniquely layered multi- reagent cartridge. A chemical reaction sequence is essentially programmed into the cartridge eliminating user intervention and the need to handle liquid reagents. Additional merits include: detection of both iodine and iodate over the required range (5-100 ppm), the cartridges and associated reader are low cost items and easy to produce on a large scale. This Phase II proposal describes research necessary to transition the test kit into a functional prototype and includes provision for independent evaluation and feedback from international experts on iodine deficiency disorders.